470 Philippine Journal of Science 1919 
TABLE III.—Analyses of silicious materials. 
{Numbers give percentages.] 
Constituent Gees | abe | Zee, | See Fae, 
Loss on ignition.___________ 0.34 0.80 5.40 0. 82 0.55 
Silica (SiOz) 97, 49 86. 60 56.00 57.54 84, 85 
Ferric cxide (raise) trace 0. 48 6.24 7.89 3.51 
Aluminium oxide (Al2Os) 1.58 8.12 19,16 20. 47 6.29 
Lime (CaO) trace 1,20 6. 18 7.31 1.65 
Magnesia (MgO) trace 0.22 4,84 3.27 2.18 
Manganese oxide (MnO2) ---| trace trace trace trace: foo 232: 
Alkalies (K20+Naz20)_.....---...._....... 0.50 ©2. 58 2.66 ©2.70 €1.02 
* Analyzed by F. Pefia, chemist, Bureau of Science. 
> Analyzed by A. S. Argiielles, chemist, Bureau of Science. 
© Determined by difference. 
ALKALI 
This material is derived from sodium carbonate or sulphate, 
which for glass making should be as nearly free from iron as pos- 
sible. Sodium carbonate, or soda ash, fuses more readily with 
Silicious material and lime than does sulphate; but, since the e 
latter is a cheaper product, it is more generally used in glass 
making, especially in the production of cheap articles. If sodium 
sulphate is used, some form of carbon should be admixed to assist 
in its reduction. Sodium carbonate and sodium sulphate, which 
are intermediate products in the preparation of caustic soda, de- 
pending upon the process used, may be imported from the United 
States or may be prepared locally from common salt. During 
1917 the Philippine Islands imported 1,423,532 kilograms of caus- 
tic soda, valued at the port of origin at 326,813 pesos. The es- 
tablishment in the Philippines of a caustic soda factory, in con- 
nection with a glass factory or a paper-pulp plant, will save to 
the Islands the value of their imports of this commodity and will 
encourage the exploitation in the Philippines of such industries 
as the manufacture of paper pulp, glass, soap, etc., all of which 
use caustic soda or one or more of its intermediate products as 
raw material. In a soda factory the largest item is fuel, and 
the next, common salt. It is believed that, by establishing a fac- 
tory in a place where there is an ample supply of firewood, and 
where at the same time climatic conditions are favorable for 
the solar evaporation of sea water, sodium carbonate can be 
produced locally at approximately 102 pesos per metric ton. 
In addition to the materials already described cullet ig in- 
variably used in commercial glass factories. The object of mix- 
